Ceramic Wastes Usage as Alternative Aggregate in Mortar and Concrete

Received May 29, 2017 Revised June 15, 2017 Accepted June 17, 2017 In the ceramic industry, huge amounts of wastes are generated during manufacturing and transportation processes. In order to decrease the need for landfill areas and increase environmentally harmful effects of such wastes, this industry is under pressure to finding effective ways for recycling its wastes and by-products. In addition, the construction industry requires new sources of aggregates due to running out of conventional virgin aggregates, saving energy, and protecting the environment. Therefore, recently, ceramic wastes are often used as coarse and/or fine aggregate both in mortar and concrete. In the present study, effects of using ceramic wastes as coarse and/or fine aggregate on the engineering properties of mortar and concrete are evaluated. These engineering properties are listed and compared according to their mechanical and durability properties. Reviewing of previous studies related with this subject in literature and discussion all results of the studies are conducted as the methodology of this study. Consequently, it was found out that the use of waste ceramic in the conventional concrete or mortar mix as fine/coarse aggregate is suitable as it can improve mechanical and durability properties of the concrete/mortar. Keyword:


Introduction
Recycling and reutilization of industrial waste and byproducts is a subject of great importance today in cement and concrete technology [1].Especially ceramic wastes, which are durable, hard and highly resistant to biological, chemical and physical degradation forces, cannot be recycled by any existing process.The use of inorganic industrial residual products in the production of concrete will lead to sustainable ceramic industry ranges from 3% to 7% of daily production [2].Therefore, construction industry can be the end user of all ceramic wastes and in this way can contribute to solve this environmental problem.The nature of construction industry, especially the concrete industry, is such that ceramic wastes can be used safely with no need for dramatic change in production and application process.On the other hand, the cost of deposition of ceramic waste in landfill will be saved and, on the other, raw materials and natural resources will be replaced, thus saving energy and protecting the environment [3].In the present study, the effects of ceramic wastes used as fine/coarse aggregates on the properties of concrete were investigated by an in-depth literature review.Thus, the effect of these ceramic wastes on the durability and mechanical properties of concrete and mortar were presented in a detailed manner.Consequently, the use of ceramic wastes and their effects as fine/coarse aggregates in a sustainable concrete and mortar were examined.

Methodology
In this study, considering the previous studies, mechanical and durability properties of concrete produced by waste ceramic addition into mortar and concrete investigated in detailed manner.Throughout the literature review, it was observed that ceramic waste was used as fine/coarse aggregate in sand/gravel in producing mortar/concrete mix.In these studies, effects of waste ceramic on the some mechanical and durability properties of concrete were investigated.In this study, mechanical properties grouped into compressive, flexural and tensile strength, elastic modulus and finally shrinkage of concrete.In addition to, durability properties grouped into water absorbtion, ultrasonic pulse velocity, chloride penetration, abrasion resistance and finally freeze-thaw resistance.Consequently, effects of waste ceramic on these properties of concrete were evaluated in a detailed manner and reasons of results were established.

Mechanical Properties
Mechanical properties of results were summarized in Table 1.Considering the results, waste ceramic was used as fine or/and coarse aggregate in concrete/mortar mixing.When ceramic waste was used as fine or/and coarse aggregate in concrete or mortar mixing, strength properties of concrete were increased compared with control concrete/mortar in generally.This improved incorporation of waste ceramic aggregate in the paste can be due to the more irregular shape it presents, resulting in a superior specific surface area than natural aggregate (gravel), which is rounded and thus lacks edges.Moreover, this irregular shape provides the higher bond between recycled ceramic aggregate and the paste.Furthermore, the ceramic aggregate could presented little puzzolanic activity in the surface part due to its chemical composition and grain size, this was nevertheless sufficient to react with the porltandite present in the periphery of the aggregate, giving rise to hydrated products such as calcium silicate hydrates (CSH) and calcium aluminate hydrates which present a less porous, more compact structure, forming a more stable aggregate/paste transition zone [4].In contrast to all these studies, a few studies consisted of low strength properties compared to conventional concrete/mortar detected [5]- [6].In these studies, the reason of strength loss was explained as ceramic aggregate having lower density and strength compared to conventional aggregate [6].

Durability Properties
Durability properties of results were summarized in Table 2.According to results of studies, chloride penetration, capillarity water absorbtion, abrasion resistance, freeze-thaw resistance, high temperature resistance, gas permeability and finally, ultrasonic pulse velocity properties were investigated in previous studies.Especially, capillary water absorbtion, oxygen and gas permeability of concrete produced waste ceramic as fine/coarse aggregate were improved or similar compared to conventional concrete.But, these properties were determined as worse compared to control specimen [7]- [8].This decrease can be due to both the higher water absorption coefficient in waste ceramic aggregate and the effect of this waste ceramic aggregate on the pore system [9].In generally, freeze-thaw durability and high temperature resistance, chloride penetration and abrasion resistance performance of concrete produced by waste ceramic were better than conventional concrete due to the high mechanical and the puzolonic properties of the ceramic aggregate [4].

Table 1 .
Comparison of some results for mechanical properties.

Table 1 .
Comparison of some results for mechanical properties (cont.).

Table 2 .
Comparison of some results for durability properties.

Table 2 .
Comparison of some results for durability properties (cont.).